The invention relates to an apparatus for pushing out stacked signatures, the apparatus having a table on which the signatures are to be stacked and having at least one push-out element which can be applied to a stack that is disposed on the table and with which the stack can be pushed away from the table.
Apparatuses of the type mentioned are known in so-called stackers or crosswise stackers and are designed to push stacked and compressed signatures away from a turntable of a stacker arrangement. In a known arrangement, a pneumatically controlled rod is integrated in the turntable for this purpose, the rod forming a so-called pusher. To push out a stack, the rod executes vertical and linear horizontal movements. During the vertical movements, the rod is lifted out of a recessed position into a position which projects beyond the turntable and is again recessed in the turntable after a horizontal movement. During the horizontal movement, the projecting rod is applied to the stack and the stack is pushed away from the table. The stack can be pushed out towards the left, towards the right or in an alternating manner. During this process, it is not possible to avoid an additional idle stroke.
The drawback of the known apparatus is that a push-out speed of approximately 1.2 m/sec. cannot be exceeded. At higher speeds, the pneumatically controlled rod executes an abrupt movement upon the stack which raises a risk that the stack tips over or that the signatures are damaged. This could be improved, per se, by way of a more complex pneumatic control, but this would be costly.